Contrast ratio (CR) has been used as a metric of display performance for presenting visible luminance differences. The contrast ratio depends on minimum and maximum luminance pixel values, e.g. pixel values of 0 and 255 in an 8-bit display system, as measured in total darkness. This metric can be modified to address performance of a display under varying ambient luminance conditions. To compute the contrast ratio under varying ambient luminance conditions, a model of a viewing scenario for displays can assume a single ambient light source. Reflected light and transmitted light can be computed based on reflectance and transmittance of a display and can be linearly superposed to the display produced minimum and maximum luminance to estimate a performance of a display based on the contrast ratio with the impact of ambient light.